There is a continuing drive towards the use of solar energy as an alternative to fossil fuels. One approach for making solar energy compete favorably with fossil fuels is to increase the power conversion efficiency while reducing the cost. Thin-film photovoltaics (PVs) such as organic polymer and amorphous silicon PVs are useful as solar cells and show promise as economically viable alternatives to fossil fuels. However, in order to compensate for their poor charge transport, the absorber thickness in these PV structures is typically limited to few hundred nanometers, resulting in incomplete light harvesting and subsequently lower power conversion efficiency.